1. Field of the Invention
This invention relates to a holding device having a flexible diaphragm acting as a suction cup, with assembled central pin. The holding device has a pressure ring which contacts the periphery of the diaphragm, and a mechanism for lifting the central pin with respect to the pressure ring.
2. Description of the Prior Art
A conventional holding device is known, for example, from British Patent GB-PS 2,185,067. The British Patent teaches a pressure ring with a top cover. A pin extends through the cover and is pulled upward by an actuating member. A helically shaped ramp pulls the pin upward. To accomplish this, it is necessary to turn the actuating member, thus there is always a danger that the pressure ring will turn along with the actuating member and slide over the diaphragm.